[meteorite-list] Metal detectors

From: Steve Schoner <steve_schoner_at_meteoritecentral.com>
Date: Thu Apr 22 10:22:39 2004
Message-ID: <20030616004931.51131.qmail_at_web12703.mail.yahoo.com>

Easy to use does not mean that just "any" detector
will do the job.

Most of the detectors are factory calibrated for coin
and gold hunting.

And most of these will simply not do for meteorite
hunting, as these detectors are made to frequency out
"iron" and iron mineralization.

Now, one can set them for iron, but then you will have
some problems with how they respond to bad high
mineral soils.

It is interesting to me how "Gold Master" works so
well for meteorites at Gold Basin, but not so well
anywhere else... why?

Soil mineralization. The soil mineralization is just
perfect for that detector at Gold Basin, but not so
true for many other areas where iron mineralization,
or salts are different.

Simple to use means, unfortunately, a turn it on and
search machine, many of which have meters that show
"coins, silver, or gold" that is being dug.

Not good for meteorites.

Get a true prospector or relic machine with two modes.
 A pure manual mode in VLF that requires ground
balance. You will get a weak steady tone when the
coil is lowered to the ground, and it will not change
when properly balanced. The machine should also have
an "automatic" mode, that is it automatically adjusts
and responds to various soil conditions.

Both modes will be required for searching for
meteorites in the various conditioins needed in the
field.

In other words, the detector must allow for the
sometimes very close balance between the soil
conditions and stone meteorites, and most stoney irons
as well.

It is interesting to note that the Lamont mesosiderite
gets factored out with most of those "coin" detectors.

The best dectectors to use are not the "easy ones"...
Instead get a good "prospector" or "relic" detector.
These often have various adjusting knobs, and it is
important to learn how to use them, and set the
machine properly.

With a good dual "manual-automatic" detector, one can
easiy switch and listen to the tone produced by each
to determine if the target is worth digging up. In
manual mode, where the tone is a just barely in the
backgound all the time, when one goes over a chunk of
metal the tone can tell the experienced user what
shape it is. If it is long and skinny, there will be
a very distinct tone difference between a sweep in one
axis compared to the other. Also, the strengh of the
signal will be different for the size of the target.
You will know whether you should get your garden
shovel out, or a large shovel to dig the piece. Most
automatic detectors give a steady solid tone
irregardless of the size of the target. They are also
harder to pinpoint the specimen, but with some
practice one can learn how to effectivy use them.

The old Gold Bug One had the capabiliyt to switch
between manual and automatic modes, and is (was)
closer to the straight manual Wilson VLF-710 in
performance than any other machine on the market.
(Wilson later came out with the "ADT" model which had
manual and automatic modes. But the mode switch was
only active for manual in pinpoint mode for finding
the exact location of the specimen. I wanted a better
control in manual rather than automatic, as I can find
meteorites with a manual machine rather than an
automatic one.

Currently, Paul Wilson is working on a simple low
frequency prospecting dectector that is "turn on and
hunt"--- in other words, a low frequency automatic.

But for me the older model with the knobs that need
adjusting seem to be better for the type of searching
that I do. And though the newer Northstar turn on and
hunt type does work very well, I have found that CB
and radio interference is a headache at times.

The bottom line with me is.

1) a prospector-relic detector. VLF-710, Gold Bug I,
or the older Garret Gold Stinger, are
"prospector-relic" types.

2) a machine without a meter other than what is needed
to show battery power, for there is no use in lugging
a meter around which only distracts rather than
helps--plus it is added weight that contributes to
fatique in sun up to sundown searching. 2.5 to 3 lbs
is suggested.

3) Very low frequency (VLF) 5 - 20Mhz) and this is a
good range for eliminating most of the terrestrial
iron mineralization, but not eliminating most
meteorites as "hot rocks."

4) A detector with both manual and automatic modes is
preferred, in other words, a "prospector-relic" model.
 But if chosing between the two, get a manual VLF
dectector.

Steve Schoner/AMS
http://www.geocities.com/american_meteorite_survey

P.S. Anyone out there have an old Gold Bug I, that
may be giving you some user frustration? I am looking
for one and would like to trade a meteorite(s) or
Polaraview for it.



    
--- Tom aka James Knudson <knudson911_at_frontiernet.net>
wrote:
> Hello Deborah and list, In choosing a metal
> detector, you have to be careful
> in your choice. You want to avoid some of the older
> detectors because of the
> complicated use. This is an excerpt from the manual
> of a older model
> detector I once used;
>
> (Some of you old timers ( 70's&80's) should remember
> this)
>
> This is from manual 5 of 7, page 982
>
> Prehunt mode:
> Turn detector on using procedures outlined in manual
> 1 & 2, chapters 5
> through 40.
> When a single beep is heard, depress buttons
> 3,7,8,12,19 and 34 at the
> same time, hold switch 4 (on bottom left) to the
> right, while simultaneously
> turning knob 8 (top right) slowly clockwise. While
> maintaining these
> settings, sweep detectors coil over the ground. Two
> beeps should sound, when
> they do, release buttons 7 & 19 flip switch 45 on
> the back of detector.
> Meanwhile, continue turning knob 8, holding switch
> 4, holding buttons
> 3,8,12 and 34. When 3 beeps are heard let go of
> buttons 34 & 8, let go of
> switch 4, let go of buttons 3 &12, stop turning knob
> 4, flip switch 45 back
> to it's starting position. Then flip switches 13,
> 22, 28,29, 32 and 73.
> You now have the detector turned on and have set the
> detector into Prehunt
> mode. Please see manual 6 of 7 to set the detector
> into hunt mode.
>
>
> Buy a easy to use detector!
>
>
> Thanks, Tom
> The proudest member of the IMCA 6168
>
>
>
> ______________________________________________
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> Meteorite-list_at_meteoritecentral.com
>
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Received on Sun 15 Jun 2003 08:49:31 PM PDT